1. Field of the Invention
The present invention relates to a recording sheet for inkjet printing comprising a sheet substrate and a receiving layer formed thereon (hereinafter referred to as “inkjet recording sheet”) and a composition suitable for forming the receiving layer.
2. Description of the Background Art
Conventionally, an inkjet recording sheet comprising a sheet substrate and a coated film (hereinafter referred to as “receiving layer”) formed by applying a coating material comprising synthetic silica and an aqueous or water-absorbent resin to the sheet substrate has been known. To ensure superior printing performance using this type of inkjet recording sheet, the receiving layer must have a large ink absorption capacity and must be hard. To increase the amount of ink absorbed by the receiving layer, increasing the amount of silica in the coating material for forming the receiving layer usually is effective.
However, if the amount of conventional water-containing synthetic silica manufactured by a precipitation method in the receiving layer is increased, the hardness of the receiving layer may decrease, giving rise to problems such as powder falling.
In addition, it has been difficult to obtain a low viscosity coating material containing a large amount of silica. If silica is dispersed in an aqueous coating material at a high concentration, a large amount of silanol groups which are present on the surface of silica form hydrogen bonds with water, resulting in an increase of viscosity due to exhibition of thixotropy.
One possible way of increasing the hardness of the receiving layer is to reduce the amount of coating material applied to the receiving layer. Reducing the amount of coating material, however, decreases the thickness of the receiving layer, which results in a decrease in the amount of ink absorbed. Another possible way of forming a hard receiving layer capable of absorbing a large amount of ink is alteration of the binder resin composition. However, simply altering the binder resin composition cannot provide a receiving layer with sufficient performance.
The present invention has been achieved in view of the above problems. An object of the present invention is to provide a composition for forming a receiving layer for inkjet printing having a low viscosity, exhibiting excellent applicability, capable of adsorbing a large amount of ink, and forming a hard receiving layer, as well as an inkjet recording sheet having a receiving layer formed from the composition.